Michel Lafontaine's use of MIDI Designer to orchestrate Solid State Symphony is featured on the official MIDI Designer YouTube channel. He points out that he's able to toggle multiple instruments simultaneously; which would be impossible using only a mouse.
User video from Michel Lafontaine. He's working with MIDI Designer Pro 2, Solid State Symphony and Cubase. Michel says: " I wanted to show up the way I use MD with Solid State Symphony. First I record the notes in Cubase and after I move the controllers to orchestrate the piece. If you see in the first few bars there is only on note in Cubase but in SSS there is many instruments playing at the same time. With MD you can, on the fly, add and remove many instruments in real time, which is impossible with the mouse. If you loop the piece you can get a totally different version each time. Thumbs up to MIDI Designer!"